This invention relates to methods and apparatus for airborne release and broadcast of loose insect eggs. More particularly, this invention relates to methods and apparatus for airborne release and broadcast of loose parasite/predator insect eggs for biological control of insect pests.
One of man's basic physical needs, food, has been the central core of his thoughts and efforts throughout the ages. Volume and quality, in the face of ever-increasing population and shrinking available land supply, remain a basic problem even in this advanced technological age. The raising of food crops, both as plants for consumption and as food for animals is dependent upon a number of basic life supporting elements. Adequate water is necessary, as well as means to replace nutrients removed from the soil by the plant life, and control of insect pests that feed upon the plants is a necessity. Irrigation and other water conservation measures have increased the availability of water in areas where natural rainfall is insufficient. Rotating crops and adding natural or chemical fertilizers has resolved the soil nutrient problem. But the balance and control of insect pests remains a critical and expensive problem in most parts of the world. It has been estimated by United States Department of Agriculture scientists that losses to insects in agriculture amount to thirteen percent of the production valued at over seven billion dollars annually.
Man, in his efforts to manipulate population ratios between different types of life on earth, has used various methods of control to include cultural, chemical, and natural. Each of these methods has a valid function in the overall regulatory process, but none in itself is completely curative in all circumstances. In today's world, man's efforts to control insect pests through extensive use of insecticides has led to some disconcerting effects on the agricultural economy and our ecological system.
During the post World War II days of the late 1940's and the early 1950's, scientific advances made toward increased production of food included many developments in agricultural chemicals. Some of these have proven to be highly beneficial while others have been very detrimental to our ecosystem. For example, while the use of fertilizer has increased crop yields, the use of insecticides has had (and continues to have) a very adverse effect upon our environment. Specific examples of these adverse effects can be noted as follows:
(1) the high level of tolerance to toxic compounds (insecticides) some insects have developed in recent years, calling for more frequent and heavier applications of poisons to eliminate the pest;
(2) an accumulation in the soil of non-biodegradable elements harmful to man;
(3) the absorption of these toxic elements by the plant both through the root system and through its foliage;
(4) recent medical research linking the consumption of these toxic substances through foods as a direct cause of certain types of diseases such as cancer;
(5) analysis of air and water samples by such agencies as the Environmental Protection Agency; and
(6) tissue analysis of both plants and animals. According to U.S.D.A. statistics, over one billion pounds of poisons are being released into the atmosphere annually over agricultural crops.
The importance of biological control of insect pests in field crops and forests has been recognized. It has long been a part of pest management systems, and is now rising to the position of prominence in overall insect pest management it deserves.
Biological control of insect pests has many advantages in our world today when we find the environment upon which our physical life depends, degenerating from man's abuse--in a time when many of our traditional sources of energy are being depleted. It is a system of control that is self-perpeturating to the extent that the host population will support. It is a renewable resource. It fits into the overall scheme of nature as it was intended.
Because of the self-perpetuating aspect of biological control, it has a more continuous effect on insect pests. Augmentative, periodic releases of parasites and/or predators or their hosts, can be made in order to manipulate population ratios necessary in maintaining the balance of nature where problems are known to exist.
For example, a small parasitic wasp, Trichogramma, or a predator insect, Chrysopa, can be a very useful biological control agent against the Heliothis complex which has a wide range of host plants--cotton, corn, soybeans, etc. Trichogramma can also be useful in control of many Lepidopterous pests which feed upon vegetables such as tomatoes bell peppers, cabbage, collards, etc. Trichogramma can be used in combatting rice leafrollers, casebearers, and webworms. They are valuable allies in the production of many crops, and they are in no way harmful to man, livestock, or to plant life. Their life span covers an approximate seven-day period, and their life cycle is nine (9) days. Its sole purpose in life is to parasitize Lepidopterous eggs. As pupae, their nourishment is derived from the embryonic fluids of the host egg, and as an adult, its nourishment is derived from droplets of dew and nectar. While further reference herein to insect eggs shall specifically be directed to the Trichogramma parasite wasp, such reference shall include any and all other parasite and predator insects that can be useful in biological control.
Research and testing by entomologists and scientists over the world has shown that biological control of insect pests is effective, and since the Trichogramma wasp is an egg parasite native to every major agricultural producing area of the world, it is a readily available source of supply as a pest insect parasite. Research has shown that concentrations of five thousand to ten thousand Trichogramma eggs per acre can effectively control a wide variety of insect pests in their egg stage. Further, the costs of biological control are a fraction of the cost of chemical insecticides and eliminate the severe ecological side effects of such pesticides.
A basic problem, however, has been that of distribution of the parasite/predator insect eggs within the desired agricultural crop or forest in which insect pest control is desired. Originally, clusters of parasitized host eggs were carried on a small paper base, such as a one-inch paper square, using a suitable adhesive to retain the eggs on the paper carrier. Typically, such a one-inch square paper base will carry five thousand Trichogramma parasitized host eggs. The eggs and the paper base carrier were manually distributed at selected intervals throughout the desired control area. As the insect parasite eggs hatched, the insect parasites were expected to uniformly spread out over the site to be controlled and parasitize the eggs of the insect pests. However, this often did not occur and if other predators found the concentrated insect egg colony on the paper carrier before the eggs hatched, a large percentage or all of the insect parasites may be destroyed, thus leaving a large "gap" in the area coverage.
Manual distribution by a man on the ground is expensive and time-consuming, and faster techniques were sought. Another technique developed was to place the paper square carrying the insect parasite eggs in a suitable container, such as a paper cup, which was then dropped from a low-flying aircraft at the desired intervals over the site to be controlled. Although faster, the technique still suffered from the disadvantages mentioned above regarding predation and non-uniformity of distribution.
Other attempts have been made to attach the parasite insect eggs, using a suitable adhesive, to granular or flaky materials such as bran flakes and to disperse such materials from an aircraft over the desired site to achieve a more uniform distribution of the eggs. However, this technique also suffers from several disadvantages:
(1) the process of adhering the eggs to the loose material is an additional process step, thus increasing the cost;
(2) the carrier material is bulky and limits the amount of egg laden carrier that can be conveniently carried by small aircraft suitable for such airborne distribution;
(3) complex metering and distribution apparatus is necessary to control the flow of the carrier material in airborne distribution; and
(4) since a large quantity of eggs are typically carried on each grain or flake of carrier material, problems of predation of a sizable percentage of the eggs still remains, particularly when coupled with the increased probability that the birds and other small animals will be attracted to and eat the carrier if it is a granular edible material such as bran or bran flakes.
It has been discovered that loose, dry parasite insect eggs can be effectively and uniformly distributed by airborne techniques utilizing the present methods and apparatus.
Accordingly, one primary feature of the present invention is to provide novel method and apparatus for uniform airborne distribution of loose, dry parasite insect eggs.
Another feature of the present invention is to provide novel method and apparatus for uniform airborne distribution of parasite insect eggs that eliminates the need for a carrier medium.
Yet another feature of the present invention is to provide methods and apparatus for airborne distribution of parasite insect eggs that requires only low-cost, lightweight and simple airborne dispensing and spreading equipment.
Still another feature of the present invention is to provide methods and apparatus for airborne distribution of parasite insect eggs that eliminates the need for large, bulky storage of carrier material.